Title: Coffee is good for the liver
Post by: sithari on September 07, 2006, 11:11:59 PM

Dr. J.B. PEIRIS and Dr. Natasha PEIRIS

It is not uncommon for liver function tests to show elevated liver enzymes or the ultra sound abdomen to show a fatty liver. There is very little that one can do to protect the liver except to abstain or reduce the consumption of alcohol and spicy food. Recent research seems to suggest that coffee is good for the liver.

Coffee and liver enzymes: Coffee drinking has an inverse relationship to gamma-glutamyl-transferase (gamma GT or GGT) production in the liver. The induction of GGT that occurs with alcohol is inhibited by coffee and thus may protect the liver against damage from alcohol excess.

In contrast, however, only a weak association between coffee intake and lower GGT levels was demonstrated in females in this study. A similar effect on the serum transaminases was also identified.

Another study reported on a cohort of 5,944 participants in the Third US National Health and Nutrition Examination Survey from 1988-1994 who had at least one of the following: excess alcohol intake, obesity, viral hepatitis, iron overload or impaired glucose metabolism.

Increased serum ALT was found in 8£7 per cent and analysis showed that lower ALT levels were associated with higher coffee and caffeine intake.

Coffee and Cirrhosis Whilst coffee consumption might improve liver enzymes in at risk subjects, does it confer protection against cirrhosis? The answer to this is probably yes. There have been a number of studies identifying an inverse relationship between coffee consumption and cirrhosis.

A Norwegian study looking at a 17-year follow-up of 5,130 adults who underwent screening for cardiovascular disease found less cirrhosis in coffee drinkers. It does appear therefore that the influence of coffee on liver function tests is not just a biochemical phenomenon, but is also protective.

Coffee and Hepatocellular Carcinoma In addition to the paper mentioned initially, reporting less HCC in coffee drinkers, there have been a number of earlier reports examining the relationship between coffee and HCC.

In 1998, La Vecchia et al examined 151 cases of HCC and reported an odds ratio of 0£78 for people who regularly drank 3 cups of coffee per day compared with non-coffee drinkers.

A similar result was reported by Kuper et al who examined 333 cases of HCC and generated an odds ratio of 0£7 for people who had a coffee consumption of 20 cups per week compared with non-coffee drinkers.

In the Gellati study, which was case-controlled, and included 250 cases of HCC along with 500 controls, a dose relationship was found. The odds ratio compared with non-coffee drinkers was 0£8 for 1-2 cups per day, 0£4 for 3-4 cups per day and 0£3 for those drinking 5 or more cups.

The inverse association was present regardless of the aetiology. This protective dose-related effect has also been suggested by recent work by Inoue et al who conducted a large-scale population based cohort study in Japan, with the most protection being seen in those drinking five or more cups per day.

Coffee: Mechanism of Action The mechanism by which coffee protects liver function and prevents HCC is unclear. Reduction of HCC may be by reducing the development of cirrhosis, the dominant risk factor. The pathogenesis of the mechanisms underlying such hepatic protection remains to be determined.

Caffeine seems to have a major role in the normalisation of liver enzymes in the USA study but whether other coffee components such as kahweol and cafestol are important is unknown.

These components influence such enzymes as gamma-glutamylcysteine synthetase, N-acetyltransferase and glutathione S-transferase involved in chemoprotection.

In addition, induction of the cytochrome P450 system, which occurs with alcohol consumption and tobacco use, has been shown to be reduced with regular coffee intake.

Diet and Chemoprotection Links between cancer and environmental influences are continually being sought, in particularly links with diet. Indeed, coffee itself has been implicated in pancreatic, bladder and colorectal malignancy.

However, the evidence for a protective effect of coffee on the liver seems both consistent and logical. Protection from injury, as evidenced by lowering serum markers of hepatic injury, such as the transaminases, might account for the lower incidence of cirrhosis and thereby reduced HCC.

Coffee is not alone is being implicated in chemoprotection against HCC. Green leafy vegetables, such as broccoli, cauliflower and Brussels sprouts, contain isothiocyanates and have also been reported to protect from HCC.

Kurozawa et al examined the dietary habits the incidence of HCC in over 1,000,000 volunteers. Interestingly, the regular intake of eggs was associated with an increased risk of HCC, while coffee and pickle intake were shown to have a significant inverse relationship.